Influence of different marginal morphology of all ceramic crown on endotoxin in gingival crevicular fluid

Objective To investigate the changes of the levels of endotoxin in gingival crevicular fluid(GCF) before and after restoration with two kinds of all-ceramic crown shoulder designs.Methods Patients whose maxillary central incisors needed all ceramic crowns were divided randomly into 90° shoulder margin group and chamfer margin group,with 20 teeth in each group.Kinetic turbidimetric assay was used to analyze the content of endotoxin in GCF before tooth reparation and 1,3,6 and 12 months after cementation.Then statistics analysis was preformed.Results 1 and 3 months after the crown restoration,the content of endotoxin in GCF in 90° shoulder margin group was obviously higher than that of chamfer margin group,showing statistically significant difference by t test(P0.05).6 and 12 months after the crown restoration in two groups,the content was different with that of two groups either before tooth reparation or 1,3 months after all ceramic crown cementation,showing statistical significance by the F test(P0.01).Two groups had no significant difference in the content of endotoxin between 6,12 months after restoration and before tooth reparation.No statistical significance was found after the F test(P0.05).Conclusions The chamfer margin of all ceramic crown is suggested to be used in preparation of all ceremic crowns.The periodontal tissue can recover six months after restoration.